Russia’s aviation regulator, Rosaviatsiya, said that all of Saratov's Airlines' flights were suspended until April 27.

Two days after the crash, investigators said that preliminary tests and analyses indicated that the speed gauges could have been covered with ice and shown inaccurate data.

The Moscow-based Interstate Aviation Committee (MAK) suggested on February 13 that heating elements for the gauges were not switched on before the An-148 took off from Moscow's Domodedovo airport on a flight to the Urals city of Orsk.

According to MAK, the flight recorders indicated that the two gauges displayed different speeds before the crash, one rising rapidly while the other showed a speed of zero.

With the difference widening, it said, the crew apparently switched off autopilot and returned to manually flying the plane, which hit the ground six minutes after takeoff.